In order to choose the best balance among approaches

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Unformatted text preview: ity engineer must address design and verification requirements for each such environment. Degree of design inheritance and hardware/software reuse. The reliability engineer should document the reliability program in a reliability program plan, which should be summarized in the SEMP (Part III) and updated as needed through the project life cycle; the summary may be sufficient for small projects. NASA Systems Engineering Handbook Integrating Engineering Specialties Into the Systems Engineering Process 6.2.3 Designing Reliable Space -Based Systems Designing reliable space-based systems has always been a goal for NASA, and many painful lessons have been reamed along the way. The system engineer should be aware of some basic design approaches for achieving reliability. These basic approaches include fault avoidance, fault tolerance, and functional redundancy. Fault Avoidance. Fault avoidance, a joint objective of the reliability engineer and quality assurance engineer (see Section 6.3), includes efforts to: • • • • • Provide design margins, or use appropriate aerating guidelines, if available Use high-quality parts where needed. (Failure rates for Class S parts are typically one-fourth of those procured to general military specifications.) Consider materials and electronics packaging carefully Conduct formal inspections of manufacturing facilities, processes, and documentation Perform acceptance testing or inspections on all parts when possible. Fault Tolerance. Fault tolerance is a system design characteristic associated with the ability of a system to continue operating after a component failure has occurred. It is implemented by having design redundancy and a fault detection and response capability. Design redundancy can take several forms, some of which are represented in Figure 29 along with their reliability relationships. Functional Redundancy. Functional redundancy is a system design and operations characteristic that allows the system to respond to component fail...
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This document was uploaded on 02/26/2014 for the course E 515 at University of Louisiana at Lafayette.

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